176 Genetic Behaviour of the Hybrid Primula Kewensis 



are small and irregular, and we must await the results of crossing lemon 

 with isabellina to prove the correctness of this hypothesis. 



P. Kewensis x i|. 



Many attempts to cross -|-| with Kewensis have been made, but 

 these crosses have generally failed. We will now give the details of a 

 cross of this nature which gave a single fertile plant. Unfortunately 

 we have not been able to count the chromosomes of this plant or of its 

 offspring. In 1915 a few hybrids of J-| x Kewensis have been obtained, 

 and we hope to continue the investigation of these hybrids, especially 

 with regard to the inheritance of the number of chromosomes. 



All attempts to cross {| with verticillata have failed. 



In 1912 Kewensis ff \_F2 ex Kewensis y. ftor. var. is-.] was fertilized 

 by i|, and gave one plant ^|, which resembled Kewensis but was not 

 very robust. This plant was self-fertilized, giving 20 plants of Kewensis, 

 differing from each othei- only as regards size. Two of the larger 

 plants were selfed and gave Kewensis, but two of the smaller plants on 

 selfing behaved differently. One such plant gave only two very small 

 plants with leaves not more than two inches long : both had somewhat 

 hairy leaves and meal in the calyx. The sister plant gave 5 plants, 4 of 

 which had also somewhat hairy leaves and meal in the calyx, but 1 had 

 hairy leaves and no meal. This plant also differed from the sister 

 plants in being pin-eyed. Hence it came near floribunda type. 

 The plant f| [/^i ex Kewensis x |^] was crossed back with If, and gave 

 two plants, one of which was typical Ketvensis; the other was small, 

 with somewhat hairy leaves and meal in the calyx. On selfing this 

 plant gave 6 plants all very near the parent plants The reciprocal 

 cross, in which jg was used as a female with ^ as male, gave one plant, 

 ne&r JJoribi(nda in type but with lemon coloured flowers. 



Although these results are slight, still they give evidence that 

 segi-egation occurs in the offspring of Kewensis x i|, giving plants in 

 which meal inside the calyx is combined with a considerable degree of 

 hairiness on other parts of the plant, and finally a single plant near 

 floribunda in type. 



These results (except that of the reciprocal cross on ||) are tabulated 

 below. 



1 The foUowiug resvilt obtained this year gives furtlier evidence as tu the consequences 

 of crossinfr the tetraploid with the diploid form. One of the 6 phxuts mentioned above, 

 derived from such an original cross, selfed gave 13 Kewensis (not yet in flower) and 

 2 iiairy plants with 1,'mon flowers, thus showing that the power of segregation is now 

 introduced. December, 1915. 



